Toronto is the largest, and the financial center, but you can't really draw a parallel to New York, it's a lot slower-paced - San Francisco actually reminded me a lot of downtown Toronto. You can easily find graduates from the top two computer science/computer engineering schools in Canada.
Ottawa had a very active tech industry before the dotcom bust, but not much after. I'm not sure today. Terribly boring city to live in, though.
Montreal would be a good choice for French speakers. There are a number of large video game studios in Montreal, I can't tell you much about start-ups there (beyond, say, http://montrealtechwatch.com/2007/07/22/poll-of-the-week-4-m... ). Culturally, a very strong city, there's always something fun going on.
Vancouver is probably the closest to San Francisco in geography and climate, I didn't know it had a strong start-up scene before I read the article on montrealtechwatch.com. It's relatively small though, not sure how easy it is to find talent (on the other hand, it's close to Seattle).
Calgary and Edmonton are booming and have a lot of oil money floating around, but skilled workers are at a premium.
But can you give an "equal to" map between US and Canada. Like SF=Vancouver. New York=Toronto etc. I will find such a map very useful.